Five seconds beep, one second pause...


var bit pwm1 is pin_c2
-- pin_c2_direction = output

 var byte lenght = 5
 var byte pause  = 1

procedure frequency ( byte in period, byte in prescale ) is
asm movf  period, w
 bank_1
asm movwf f877_pr2
 bank_0
  f877_ccpr1l = period / 2       -- set duty cycle at approx 0.5
  pin_c2_direction = output

   if prescale == 16 then
     f877_t2con = 0b_0000_0110   -- tmr2 on, prescale=16
   elsif prescale == 4 then
     f877_t2con = 0b_0000_0101   -- tmr2 on, prescale=4
   elsif prescale == 1 then
     f877_t2con = 0b_0000_0100   -- tmr2 on, prescale=1
   end if
  f877_ccp1con = 0b_0000_1100    -- pwm mode on
end procedure


procedure stop is
 delay_1S ( lenght )
 f877_ccp1con = 0             -- PWM off
 delay_1S ( pause )
end procedure

procedure DO1  is frequency ( 238, 16 ) stop end procedure
procedure MI1  is frequency ( 189, 16 ) stop end procedure
procedure SOL1 is frequency ( 158, 16 ) stop end procedure
procedure DO2  is frequency ( 118, 16 ) stop end procedure


-- main program

forever loop

 DO1  MI1 SOL1  DO2

end loop




On Thu, 18 Jan 2001, Tom Mariner wrote:

> Is this a trick question? Out of the infinite ways of  bit banging and
> hardware, I would choose to use the PWM.
>
> On the other hand, I'll bet that there is something else going on in the
> device or you would be using a 12 series. The deal is to write your code
> with a mini-RTOS so that lots of things can happen "at once". I still would
> fire up the PWM and let it do its task if a square wave is all that is
> required. I'd still use the PWM for the sampling frequency if a more complex
> audio waveform is needed.
>
> Tom Mariner
>
> -----Original Message-----
> From:   pic microcontroller discussion list [mailto:PICLIST@MITVMA.MIT.EDU] On
> Behalf Of Paul Chicofsky
> Sent:   Wednesday, January 17, 2001 5:40 PM
> To:     PICLIST@MITVMA.MIT.EDU
> Subject:        [PIC]:PIC16F877
>
> Hi all
>
> Any body know how to program the pic16f877 so it outputs a beep to a speaker
> for only 5 seconds?
>
> Thank you
>
> Samer
>
> _________________________________________________________________________
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